How good is Jscan!?

[ShadowsPapa]

I have both AlfaOBD and JSCAN. JSCAN is a bit easier, IMO, and allows nice screens for troubleshooting (you can show misfires on all cylinders in a grid, among many other things.
With the bypass cable and BT adapter in place, you can even up your idle speed with JSCAN when running a winch or anything else where you are better off running the alternator faster than idle speeds.
I do like AlfaOBD - it does great freeze-frame captures and crazy good logging - better logging than JSCAN, but I find which I use depends on what I am doing.
I can, for example, keep the app open on my phone and watch EHPS pump operation if I was having a problem, turn things off and on and again, up the idle speed for times I need more electrical power.
It's like a lot of other tools I have - there's no one ratchet or wrench or screwdriver that always works best for each situation.

Want to watch your SelecTrac transfer case (or RockTrac full time automatic transfer case) - in action?

Then the logging in AlfaOBD is nice -

2021/01/04 11:56:32.011: Faults found: P0303
2021/01/04 11:56:35.970: Faults found: P0303
Error code: P0303
Cylinder 3 ignition failures
Test not complete
Error intermittent
Error warning lamp not requested
CARB Freeze Frame:
___________________
Fault code: P0303
PCM Mileage since MIL On: 0.00 miles
PCM Odometer: 950.27 miles
Open Loop - Bank 1: No
Closed Loop - Bank 1: Yes
Open Loop due to Driving Conditions - Bank 1: No
Open Loop with DTC - Bank 1: No
Closed Loop with DTC - Bank 1: No
Open Loop - Bank 2: No
Closed Loop - Bank 2: No
Open Loop due to Driving Conditions - Bank 2: No
Open Loop with DTC - Bank 2: No
Closed Loop with DTC - Bank 2: No
Engine load: 30.20 %
Freeze Frame Engine Coolant Temp: 66.00 Deg.C
Intake Air Temperature: 215.00 Deg.C
Ambient Air Temperature: 12.00 Deg.C
Short Term Fuel Trim - Bank 1: 12.49 %
Long Term Fuel Trim - Bank 1: -3.13 %
Short Term Fuel Trim - Bank 2: 9.37 %

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[Sigz]

Well I updated my tires with Jscan this afternoon (should have done it a 12000 miles ago when I purchased my JT and bought 285/70/17 at3ws). Waze gps and my jeep are pretty darn close. Maybe 1mph off… if it’s off.


I drove around for a bit today and the shift points aren’t as jerky - they seemed more refined and fluid. Although - it seems that I have now lost 8th gear - which is a little weird.

Usually hit 8th on a stretch of drive on my way home from work which is around 50mph but it seemed to just be happy in 7th.

 

[GA D90]

I have both AlfaOBD and JSCAN. JSCAN is a bit easier, IMO, and allows nice screens for troubleshooting (you can show misfires on all cylinders in a grid, among many other things.
With the bypass cable and BT adapter in place, you can even up your idle speed with JSCAN when running a winch or anything else where you are better off running the alternator faster than idle speeds.
I do like AlfaOBD - it does great freeze-frame captures and crazy good logging - better logging than JSCAN, but I find which I use depends on what I am doing.
I can, for example, keep the app open on my phone and watch EHPS pump operation if I was having a problem, turn things off and on and again, up the idle speed for times I need more electrical power.
It's like a lot of other tools I have - there's no one ratchet or wrench or screwdriver that always works best for each situation.

Want to watch your SelecTrac transfer case (or RockTrac full time automatic transfer case) - in action?

Then the logging in AlfaOBD is nice -

2021/01/04 11:56:32.011: Faults found: P0303
2021/01/04 11:56:35.970: Faults found: P0303
Error code: P0303
Cylinder 3 ignition failures
Test not complete
Error intermittent
Error warning lamp not requested
CARB Freeze Frame:
___________________
Fault code: P0303
PCM Mileage since MIL On: 0.00 miles
PCM Odometer: 950.27 miles
Open Loop - Bank 1: No
Closed Loop - Bank 1: Yes
Open Loop due to Driving Conditions - Bank 1: No
Open Loop with DTC - Bank 1: No
Closed Loop with DTC - Bank 1: No
Open Loop - Bank 2: No
Closed Loop - Bank 2: No
Open Loop due to Driving Conditions - Bank 2: No
Open Loop with DTC - Bank 2: No
Closed Loop with DTC - Bank 2: No
Engine load: 30.20 %
Freeze Frame Engine Coolant Temp: 66.00 Deg.C
Intake Air Temperature: 215.00 Deg.C
Ambient Air Temperature: 12.00 Deg.C
Short Term Fuel Trim - Bank 1: 12.49 %
Long Term Fuel Trim - Bank 1: -3.13 %
Short Term Fuel Trim - Bank 2: 9.37 %

I had no idea it displays and logs data, very cool!
Ok, you all have convinced me…getting the license and hooking it up!
One more question, I can leave the bypass cable connected?
Thanks!

 

[Hootbro]

Well I updated my tires with Jscan this afternoon (should have done it a 12000 miles ago when I purchased my JT and bought 285/70/17 at3ws). Waze gps and my jeep are pretty darn close. Maybe 1mph off… if it’s off.


I drove around for a bit today and the shift points aren’t as jerky - they seemed more refined and fluid. Although - it seems that I have now lost 8th gear - which is a little weird.

Usually hit 8th on a stretch of drive on my way home from work which is around 50mph but it seemed to just be happy in 7th.

I would suggest a "All Adaptive Memory" reset. That way the adaptive memory can re-baseline with your new settings.

 

[Sigz]

I would suggest a "All Adaptive Memory" reset. That way the adaptive memory can re-baseline with your new settings.

Thanks for that. Can you go into detail about what this really does? (Sorry, totally noobish with all this).

 

[ShadowsPapa]

Especially the transmission.......... I noticed that when our JLU received the "new" transmission, the first trip or two were not as slick and seamless in shifting, you could feel the shifts, then it adapted and learned and now it's as smooth as ever - can't tell without looking.

 

[Hootbro]

Thanks for that. Can you go into detail about what this really does? (Sorry, totally noobish with all this).

PCM over time learns your driving style and adapts the shift points. Changing the tire size without resetting the memory may have skewed that.

Going to 33's on a Sport with 3.73 gears is on the upper margins of the shift points. I had to do the same reset when I put 285/70/17's on my 2021 Willys with 3.73 gears. Once I did that and the tire size correction, it saw 8th gear a lot more.

 

[Sigz]

PCM over time learns your driving style and adapts the shift points. Changing the tire size without resetting the memory may have skewed that.

Going to 33's on a Sport with 3.73 gears is on the upper margins of the shift points. I had to do the same reset when I put 285/70/17's on my 2021 Willys with 3.73 gears. Once I did that and the tire size correction, it saw 8th gear a lot more.

Okay, thanks for the tip. Will try this! Darn, and I put the panels back and thought I didn't have to get back to those two cables underneath the steering wheel!

Can I ask (if you remember) what tire size did you input into JSCAN with your 285/70/17?

Also - if I don't reset the memory, will the JT "learn" the shift points eventually?

 

[Sigz]

Especially the transmission.......... I noticed that when our JLU received the "new" transmission, the first trip or two were not as slick and seamless in shifting, you could feel the shifts, then it adapted and learned and now it's as smooth as ever - can't tell without looking.

Did you end up using the "All Adaptive Memory" reset in JSCAN? Or did it adapt on its own after you changed the tire size?

 

[Hootbro]

Can I ask (if you remember) what tire size did you input into JSCAN with your 285/70/17?

I do not remember. Tire sizes even across the different brands are not exactly the same for a given stated label size. You have to actually tape measure your tire and wheel combo at pressure and weight on wheel. Jscan IIRC goes in 1/4" increments and even then, you may have to go up/down a few times to get it dialed in. You want to bump it against a GPS reference speed.

Also - if I don't reset the memory, will the JT "learn" the shift points eventually?

In theory I think it would but I do not know the over time buffer length the adaptive memory learns.

You can also do the adaptive reset the caveman way and disconnect both batteries for like 20-30 minutes and reconnect. Owners manual should have instructions on disconnecting both batteries without have to go inside direct to the aux battery.,

 

[ShadowsPapa]

Owners manual should have instructions on disconnecting both batteries without have to go inside direct to the aux battery.,

That's not too bad - take both cables off the top of the IBS, take the cables apart from each other, don't let either ground cable touch anything for that amount of time.
The aux battery grounding up at the main battery point is at least one small "blessing" for us. What a pain in the #@$$ had they forced us to rip the truck apart to disconnect that aux ground.

 

[Raven65]

Can I ask (if you remember) what tire size did you input into JSCAN with your 285/70/17?

I went from the stock Sport S wheels/31's to Rubicon take-off wheels with the original Wildpeak 285/70-17 33's - and I plugged in a height of 32.7". I believe I found that on here somewhere from a Rubicon owner who said that's the height his showed stock. Anyway, my speedo is right in line with my GPS. It may 1 MPH one way or the other occasionally, but I chalk that up to the GPS lag.

 

[Pismo61]

I bought a license, dongle, and bypass cable in 12/22 for a total of $83.86. I've only used it once so far to correct my speedo after upgrading from the stock Sport S 31" pizza cutters to stock Rubicon take-off wheels/33" tires. Hooked everything up, made the change, unplugged everything... haven't touched it since. At some point I'll upgrade all the lighting to LED and will go back in and change the setting for that. I didn't see the need to spend 3x that for a Tazer just to do that. It's a little intimidating and not completely intuitive at first if you've never down anything like this, but it's not bad. There are several YouTube videos out there that show you step by step how to use it. The hardest part is connecting/disconnecting the bypass cables... it's tight up in there. Buying the extension cables is a really good idea if you think you're going to use it a lot.

X2 my experience also.

 

[Sigz]

I went from the stock Sport S wheels/31's to Rubicon take-off wheels with the original Wildpeak 285/70-17 33's - and I plugged in a height of 32.7". I believe I found that on here somewhere from a Rubicon owner who said that's the height his showed stock. Anyway, my speedo is right in line with my GPS. It may 1 MPH one way or the other occasionally, but I chalk that up to the GPS lag.

Thanks.

Did you end up resetting the all adaptive memory in Jacan? Did ya lose 8th gear?

 

[Raven65]

Thanks.

Did you end up resetting the all adaptive memory in Jacan? Did ya lose 8th gear?

I did not. I saw 8th less often, but I figured that was to be expected given the (slightly) taller tires. They're also wider & softer. More aerodynamic drag and more rolling resistance. I aired them up to 37-38 lbs, but on a couple of real cold mornings (and "real cold" here in SC is 30* or so LOL) the pressures would drop to 32-33 lbs or so... and I could feel the extra drag... noticed that I saw 8th even less. When the tires heat up and pressures are where they should be, I see 8th more. Generally I'll see 8th on flat ground up to about 70-75 MPH (if I'm remembering correctly). Anything above that, it drops to 7th due to the wind resistance.

It's been over a year, so I assume the adaptive shifting has... adapted by now. I wonder if I'd have anything to gain be resetting it at this point?

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